Oil-fired furnace



A131519, 1963 G. PEoPLEs ETAL 3,084,682

- OIL-FIRED FURNACE Filed Sept. 14, 1959 4 Sheets-Sheet 1 lf/iff@ 26 INVENTORS ATTORNEYS.

April 9, 1963 G. PEoPLEs ETAL 3,084,682

OIL-FIRED FURNACE Filed Sept. 14, 1959 4 Sheets-Sheet 2 April 9, 1963 G. PEoPLEs ETAL 3,084,682

Y OIL-FIRED FuRNAcE Filled Sept. 14, 1959 4 Sheets-Sheet 5 l I l I l l ATTORNEYS April 9, 1963 G. PEoPLEs ETAI.

OIL-FIRED FURNACE 4 Sheets-Sheet 4 Filed Sept. 14, 1959 /NVENTOR$' d/ 0% ATTORNEYS.

BVMW

United States Patent Marshalltown,

Marshall- This invention relates generally to an oil-tired furnace unit, and more particularly to a novel furnace and heat exchanger construction of extreme compactness and low vertical height capable of achieving more efficient operation than oil furnaces of substantially greater size.

In the assembly of heating and all-season air conditioning systems of the modular stack type, the achievement of compact unit size with high operating efficiency is critical to commercially acceptable equipment. Such modular stack systems are disclosed and described in the co-pending application of John W. Norris, Serial No. 755,785, filed August 18, 1958, now Patent No. 3,012,762, granted Dec. l2, 1961, and having a common assignee with the present invention.

It is the primary object of this invention, therefore, to provide a new and improved heat exchanger construction for `an oil-tired furnace unit, wherein extreme cornpactness of size is achieved in an oil furnace that operates more efficiently than previously known oil-red furnace units of substantially greater size.

It is another object of this invention to provide an oil- =f`1red furnace unit characterized by a novel arrangement of narrow clamshell-type heating sections, wherein an extremely low over-all vertical -unit height is achieved through an upward vand lateral combustion gas flow pattern, with all combustion products passing through the heat exchanger substantially at right angles to the path of maximum velocity of air flow.

Further objects and advantages of this invention will become apparent `as the -following description proceeds, and the features of novelty which characterize this invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

A preferred embodiment of the invention is shown in the accompanying draw-ing, in which:

FIGURE 1 is a fragmentary view in front elevation of a modular stack arrangement of air .treating units, wherein the oil-tired furnace unit of the present invention is included.

FIGURE 2 is a Ifragmentary perspective view with parts removed of the heat exchanger of a furnace unit constructed in accordance with the present invention.

FIGURE 3 is -another perspective View, similar to FIGURE 2, with parts removed and separated for purposes of exposition.

FIGURE 4 is a side elevational view of the unit of FIGURE 2.

FIGURE 5 is a cross sectional view of the unit of FIGURE 2. at the combustion inlet end -substantially as indicated by the line 5-5 on FIGURE 6; and

FIGURE 6 is a fragmentary cross sectional view showing the details of structural assembly of the corbel discharge outlet of the furnace drum.

Referring now more particularly to FIGURE 1 of the drawing, we have indicated generally at 10 an oil-fired furnace unit constructed in accordance with the principles and features of the present invention. The unit 1t) is shown in vertically stacked relation on top of a blower unit 12 and below a cooling coil or similar unit 14 of an all-weather air conditioning system. Reference may be made to the said co-pending application of lohn W. Norris for a more complete description of the advantages and features of a modular stacked assembly of separate air ice handling and treating units. It will be understood that, in connection with such modular stack systems, it is irnportant to achieve a low over-all vertical height, while at the same time maintaining a uniform horizontal crosssectional size of minimum extent. The design of the furnace unit `10, as hereinafter described, `achieves these dimensional restrictions while at the same time providing a high efficiency of operation exceeding that of presently known units of substantially larger size.

The oil-tired furnace unit 10 comprises a heat exchanger 26 for oil combustion and heat transfer between the combustion products and a flow of air to be transmited to a room space. The heat exchanger 20 is best seen in FIGURES 2 and 3 of the drawing, and is adapted to receive a suitable gun-type oilburner 22 in cooperative relation, as indicated in FIGURE 1.

The heat exchanger 2t) comprises a vestibule panel 24 extending vertically along substantially the Vfull face area of the unit 10. A plurality of hollow heat exchange units 26 are fixedly secured to the vestibule panel 24, las by welding, in spaced side-by-side vertical assembly. The heat exchange units 26 are fabricated in the Well-known manner, as will be later described in detail, by metal half-shells peripherally bonded together to deiine the hollow units which are commercially termed clamshell-type. A lframe channel 28 provides further rigidity and support for the clamshell units.

A combustion chamber drum 30, having a frustoconical member 32 providing a discharge outlet 32a, is mounted at the combustion inlet end of the clamshell units 26. An outer end wall 34 provides an external closure for the drum 30. A collecting breech 36, providing a pair of conducting chambers 3S and 40, serves to conduct the discharging combustion products from the clamshell units 26 to a flue transition 42. A suitable ilue 44 serves to conduct the combustion products away from the unit 10.

The drum 30 is formed with an oil-tiring inlet opening 46. An oil burner tube 48 extends from the drum opening 46 through a suitable opening 50 in the vestibule panel 24. As best seen in FIGURE 4 of the drawing, a looking strap with bolt means 52 serves to iixedly secure the tube 48 in mounted relation with the vestibule panel 24. The conducting chambers 38 and 40 also extend through suitable openings in the vestibule panel 24 for communication with the flue transition 42. As seen in FIGURE 2, the vestibule panel 24 provides a removable cleaning plate 54, and a smaller inspection door 56 for access to the interior of lthe clamshell units 26.

Referring again to FIGURE 4, 4the clamshell units 26 will now be more particularly described. As i-s well known in the art, the clamshell units 26 are formed by a series of half-shell segments assembled in consecutive side-by-side relation. The first half-shell at the lefthand end of FIGURE 4 (see also FIGURE 6) constitutes a left chamber end clamshell `60. A right-forming clamshell 62 cooperates with the clamshell 60 to provide the rst clamshell unit. In a similar manner, the next adjacent left-forming clamshell 64 cooperates with another right-forming clamshell 62 to define a center clamshell unit. As seen in FIGURES 3 and 5, the clamshells 60 and `62 are ea-ch provided with a pair of diagonally converging rib embossments s63 for purposes of mechanical reinforcement against the effects of cyclical heating `and cooling during practical operation. Successive center clamshell units are similarly formed as desired, four center clamshell uni-ts being shown intermediate the end clamshell units. A right chamber end clamshell 66 cooperates with. a left-forming clamshell 64 to deiine the last clamshell unit. 'I'he several pairs of left and rightforming clamshells are peripherally welded together at their marginal edges 767--672 as best seen in FIGURE 6i. In addition, the clamshell half units provide intermediate connecting wall portions or collars peripherally inwardly thereof of generally annular form, which are similarly welded together, as indicated at 68 and 79' in FIGURES 3 and 4 of the drawings. In this way, a main flow conduit l618 and a return ilow conduit 7i) (see also FIGURES 3 and 5) are defined by the clamshell units 26. Access ports 7.2 are provided by each of the clamshell units 26 at `their lower ends for communication through the vestibule panel 24 by means of the cleaning plate S4. In this way, 80% cleanability with a brush is achieved by removal of the single access plate.

In order to provide proper temperature control of the combustion gases, and -to regulate the pattern of hot gas flow, supplementary bailling means are included within the flow conduits 68 and 7i?. As best revealed in FIG- URES 3 and 4, a semi-cylindrical baille 74 surrounds the upper half portion of the main ilow conduit 68 so as to direct the combustion gas `flow into the downwardly hollow interiors of the clamshell units 26 for consequent lateral and upward flow therethrough toward the return flow conduit 70 at the upper end of the assembly. A stainless steel target 76 of inwardly convex shape is carried by `the right chamber and clamshell 66 to prevent hot-spot erosion of the right chamber end. A plurality of trapezoid-shaped iin bailles 78, 8d, and `tif?. are secured intermediate three of the center clamshell units and the right chamber end clamshell unit, as best seen in FIGURES 4 and 5. The iin baffles 78-82 provide added heat exchange and cooling of the clamshell surfaces.

It is a highly important feature of the present invention, in connection with the achievement of highly efiicient heat transfer within a minimum vertical unit heigh-t, that Ithe return flow conduit 'lil is only slightly above but substantially laterally displaced -to one side of the main flow conduit 68, as clearly revealed in FIG- URES 3 and 5. Flow arrows have been superimposed over FGURE to reveal ythe general pattern `of combustion gas ilow Ifrom the discharge outlet 32a of member 32 Iand main ilow conduit y68 to the return conduit 70, and the air supply flow upwardly between the clamshell units l26. For purposes of exposition in FIG- URE 5, the upward flow of air through the clamshell units has been indicated by double-head arrows, and the generally lateral ilow of combustion gases by singlehead arrows. The upwardly moving air ilow to be heated by engagement with the outer surfaces of the clamshell units 26 is rst directed against the hottest discharge gases, so as to achieve the important efficiency advantages of direct engagement -between the coolest air and the hottest gases. The baille 74 serves to direct the hot gases 4laterally downwardly into the interiors of the clamshell units 26, and then upwardly therethrough in a lateral direction toward the return flow conduit 76. It will be apparent that all of the combustion products pass at substantially right angles to rthe path of maximum ve- `locity of air flo-w.

Referring now to FIGURE 6 of the drawing, the combustion chamber drum 3tlrnay be lined with a suitable refractory material 84, such as a mat of woven refractory fibers, or `it may be formed as a unitary cast refractory chamber, as desired. The frusto-conical member 32 is preferably formed of cast refractory material, and is supported at the outlet end of the drum 30 by means of a `generally frusto-conical support collar 86 provided by the ileft chamber end clamshell i6). The member 32 is -set in and projects from the face of the left chamber end clamshell `60, and is therefore commonly referred to in ycommercial furnace and heat exchange structures as a corbel An annular shoulder 88 of generally -frustoconical form is defined by the corbel 32 for seated and sealing engagement with the refractory liner `34%. The

corbel 32 adds additional heating surface to the combusion chamber drum Sti, while telescoping into the clamshells 26 so as -to provide more time to complete the burning of the fuel oil before contact of the combustion products with the relatively cold surfaces of the clamshells.

lIt its also an important feature, in connection with the contro-l of heat transfer eiliciency, that the collect/ing breech 36, which receives the discharging combustion gases from the return ilow conduit 70, ris split into the two separate lateral conducting chambers 38 and 40. ln this way, additional cooling surfaces for the discharging gases are provided, while achieving a reduction in stack temperature that is far greater than would be expected from the mere area addition of metal surfaces. In this way, higher than expected combustion rates can be achieved within the extremely compact size of the unit 1t). The ilue gas velocity and the air velocity ratio are balanced for high eiliciency because of the particular size and spacing of the clamshell units 26. In practice, clamshells of an over-all width of one inch and an adjacent spacing of l1/2 inches are employed thereby achieving a minimum resistance to `air flow equivalent to a corresponding gas-tired furnace unit. In this way, the unit il@ has been designed for full interchangeability with gas-fired units in the same over-all modular stack sys-tem employing the same blower unit.

While there has been shown and described a particular embodiment of this invention, it will be obvious to those skilled in the yart that various changes and modifications may be made .therein Without departing from the invention and, therefore, it is intended in the appended claims to cover `all such changes and modifications as fall within the true spirit and scope of the invention.

What we claim as new Iand desire to secure by Letters Patent .of the United States is:

l. A furnace construction comprising an elongated drum defining `a combustion chamber, said drum having an inlet for receiving a combustible fuel and air mixture and having an outlet for discharging combustion gases therefrom, a plurality of hollow clamshell heat exchange units of relatively narrow width and large lateral area arranged in spaced face to face vertical relation, said heat exchange units providing intermediate connecting wall portions peripherally inwardly thereof to collectively deline an elongated main ilow conduit and an elongated return ilow conduit therethrough, said return flow conduit -being disposed parallel to, above, and laterally displaced to one side of Said main ilow conduit, baille means disposed Within the upper portion of said main flow conduit, said ilow conduits being in lateral flow communication with each other through said consecutively-spaced clamshell units, thereby to deilne a combustion gas ilow path from said drum into said main ilow conduit and progressively along its length, said baille means directing said ilow initially downwardly therefrom for subsequent ilow progressively along the length of said main flow conduit upwardly and laterally through said hollow clamshell units to said return flow conduit, fin means carried by at least one of said clamshell units to provide added heat exchange surface therefor, and collecting breech means at the outlet end of said return flow conduit to conduct combustion gases for discharge.

2. A furnace construction comprising an elongated drum dening a combustion chamber, said drum havin-g an inlet for receiving a combustible fuel and air mixture and having 'an outlet for discharging combustion gases therefrom, la plurality of hollow clamshell heat exchange units of relatively narrow width and large lateral area arranged Iin spaced face-to-face Vertical relation, said heat exchange units providing intermediate connecting wall portions periphenally inwardly thereof opposite said return ilow Iconduit to collectively define an elongated main ilow conduit therethrough directly communicating with said drum outlet and an elongated return flow conduit yadapted to communicate with a flue, said return iiow conduit being disposed parallel to, above, and laterally displaced to one side of said main iiow conduit, said flow conduits being in later-al iiow communication with each other through said consecutively-spaced clamshell units, thereby to define a combustion gas flow path from said drum into said main low conduit and progressively along its length upwardly and laterally through said clamshell units to said return ow conduit, and vertical panel means supporting said heat exchange units at their lower ends at the side thereof, said clamshell units having access openings at said lower ends enclosed by and accessible only through said panel means.

3. A furnace construction comprising an elongated drum detining a combustion chamber, a burner, said drum having an inlet coupled tto said burner for receiving a combustible fuel and air mixture and having an outlet for discharging combustion gases therefrom, a plurality of hollow clamshell heat exchange units of relatively narrow widths `and large lateral `area arranged in spaced face-to face vertical relation, said heat exchange units providing intermediate connecting wall portions peripherally inwardly thereof tto collectively deiine :an elongated mai-n flow conduit therethrough directly communicating with said drum outlet and an elongated return flow conduit adapted to communicate with a ilue, said drum outlet comprising a rusto-conical member positioned within said main flow conduit for discharging combustion gases from said drum into said main llow conduit, said return flow conduit being disposed parallel to, above, and laterally displaced to one side of said main flow conduit, the physical relationship between the main ow conduit and the return flow conduit within .the hollow clamshell heat exchange units providing highly efficient Iheat transfer within a limited vertical unit height, said flow conduits being in lateral ilow communication with each other through said consecutively-spaced clamshell units, thereby to define a combustion gas flow path from said `drum into said main llow conduit and progressively along its length upwardly and laterally through said clamshell units to said return ow conduit.

References Cited in the file of this patent UNITED STATES PATENTS 1,873,579v Frantz Aug. 23, 1932 2,983,493 Herbert June 8, 1937 2,121,108 Tuck June 21, 1938 2,157,643 Westwick May 9, 1939 2,159,440 Livar May 23, 1939 2,173,280 LeTourneau Sept. 19, 1939 2,267,905 Frantz Dec. 30, 1941 2,568,487 Carowell Sept. 18, 1951 2,658,504 laye et al Nov. 10, 1953 2,752,126. Crone June 27, 1956 FOREIGN PATENTS 513,557 Canada June 7, 1955 

1. A FURNACE CONSTRUCTION COMPRISING AN ELONGATED DRUM DEFINING A COMBUSTION CHAMBER, SAID DRUM HAVING AN INLET FOR RECEIVING A COMBUSTIBLE FUEL AND AIR MIXTURE AND HAVING AN OUTLET FOR DISCHARGING COMBUSTION GASES THEREFROM, A PLURALITY OF HOLLOW CLAMSHELL HEAT EXCHANGE UNITS OF RELATIVELY NARROW WIDTH AND LARGE LATERAL AREA ARRANGED IN SPACED FACE TO FACE VERTICAL RELATION, SAID HEAT EXCHANGE UNITS PROVIDING INTERMEDIATE CONNECTING WALL PORTIONS PERIPHERALLY INWARDLY THEREOF TO COLLECTIVELY DEFINE AN ELONGATED MAIN FLOW CONDUIT AND AN ELONGATED RETURN FLOW CONDUIT THERETHROUGH, SAID RETURN FLOW CONDUIT BEING DISPOSED PARALLEL TO, ABOVE, AND LATERALLY DISPLACED TO ONE SIDE OF SAID MAIN FLOW CONDUIT, BAFFLE MEANS DISPOSED WITHIN THE UPPER PORTION OF SAID MAIN FLOW CONDUIT, SAID FLOW CONDUITS BEING IN LATERAL FLOW COMMUNICATION WITH EACH OTHER THROUGH SAID CONSECUTIVELY-SPACED CLAMSHELL UNITS, THEREBY TO DEFINE A COMBUSTION GAS FLOW PATH 